Fix PRAIN=precip_total_tend in P3?

I think precip_total_tend (known as PRAIN in pbuf and output) is supposed to be rain + snow production (i.e. the things that create rain without things like evaporation that deplete rain). It is mistakenly(?) labeled "Total precipitation (rain + snow)" in several places in the code.

I *think* it is only used as a diagnostic output. I also think it is defined incorrectly in P3:
https://github.com/E3SM-Project/scream/blob/4575d088af4d87cf44f4b7fbcf8eae5e965d5024/components/eam/src/physics/cam/micro_p3.F90#L862
. qccol is collection of qc by ice - I'm not sure why it has such an archaic name. This equation looks to me to be ignoring most sources of ice (like vapor deposition, etc). Is precip_total_tend supposed to just be conversion from qc to qr+qi? Why would anyone want that?

Because PRAIN/precip_total_tend seems to just be used for output and has a definition that I can't understand even when I look at its source code, I suggest just deleting it. Does anyone know why we shouldn't?

@AaronDonahue , @hassanbeydoun , @JS-WRF-SBM - do you have any opinion? Have we discussed this before?